Washington County Lake Quality
Maine, 11 lakes, average grade A (Excellent)
Only 11 lakes in Washington County carry an active grade. The county-level summary is therefore representative of those specific lakes, not necessarily of every water body in the county. The county's average grade is A — among the cleanest in Maine. 11 lakes pull an A on their own, and almost none fall into the D or F brackets.
The county's lakes lean shallow, which makes the grades sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest lake on the books is Big Lake (A); the most-stressed is Big Lake (A).
Quick Answers for Washington County
Planning a trip? Check special fishing regulations for Big Lake — or check the official Maine fishing regulations.
All Lakes in Washington County
11 lakes11 graded lakes
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| 1 | ABig LakeWashington | A | 16.7 ft | 8 µg/L | 2.7 µg/L | No recent samples | Not recorded |
| 2 | AEast Musquash LakeWashington | A | 20.5 ft | 5.5 µg/L | 3 µg/L | No recent samples | Not recorded |
| 3 | AGrand Falls Flowage LakeWashington | A | 14 ft | 10 µg/L | 3.7 µg/L | No recent samples | Not recorded |
| 4 | ALewey LakeWashington | A | 15 ft | 9 µg/L | 3 µg/L | No recent samples | Not recorded |
| 5 | ALong LakeWashington | A | 15.6 ft | 8.5 µg/L | 3 µg/L | No recent samples | Not recorded |
| 6 | APleasant LakeWashington | A | 27.2 ft | 5.5 µg/L | 2 µg/L | No recent samples | Not recorded |
| 7 | APocumcus LakeWashington | A | 27.9 ft | 4 µg/L | 2 µg/L | No recent samples | Not recorded |
| 8 | AScraggly LakeWashington | A | 19.4 ft | 8 µg/L | 3 µg/L | No recent samples | Not recorded |
| 9 | ASysladobsis LakeWashington | A | 27.8 ft | 6 µg/L | 2 µg/L | No recent samples | Not recorded |
| 10 | AWest Grand LakeWashington | A | 36.7 ft | 3 µg/L | 1 µg/L | No recent samples | Not recorded |
| 11 | AWest Musquash LakeWashington | A | 31 ft | 4 µg/L | 2 µg/L | No recent samples | Not recorded |
Lake Match
Which lake suits how you actually use one?
Six questions — swimming, fishing, quiet, cabins, drive time — and a shortlist of graded lakes that fit, with the water quality behind each one.
Other Counties in Maine
See how Washington County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 39 states and 2 Canadian provinces.
Where to stay near Washington County
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Source: EPA National Aquatic Resource Surveys, 2026.